Girder for struts or the like



June 8, E937. c. DoRNlER GIRDER FOR STRUTS 0R THE LIKE me@ oct. 1e. 1932 ser.:

for.'

Patented June 8, 1937 n .UNITED STATES PATENT OFFICE.

Metallbanten G. m. b. H., Friedrich'schai'en-onthe-Bodensee, Germany duplication October 18, 1932, Serial No. 638,348 In Germany October 28, 1931 i@ Claims.

My invention relates to girders, more particularly such as are adapted for use as spars in the wings of aercplanes.

` It has heretofore been proposed to construct such spans with chords and webs, the webs having the form of a framework or f iull or openwork sheet metal webs. Since the chords are also mede ci sheet metal, the connection between the webs and the chords has been edected by means luci angles riveted to the chords and webs, respec y tively, st least two rows of rivets being required for securing each angle iron in place. It is. an object of my invention to simplify the construction oi girders of this kind, by designing the chords as drawn or rolled shapes ci substantially rectangular cross section with substantially rectangular anges formed on one side, which serve for fixing the webs thereto. Preferably each chord is formed with at least three iianges so that if desired several webs can he provided between the chords of each girder.

In self-supporting girders the width of the chords may decrease from the iixed end -towards the free end oi. the girder, the webs being secured to the outer flanges near the xed end and'to the inner flanges near the free end, the contour of the chords being narrowed down by milling or the like from the fixed towards the free end. The width may decrease gradually or uniformly according to a straight line or a curved line, for instance, a parabola. The distance between the webs is chosen in accordance with the number of anges on the chords. Consecutive webs secured to the inner and outer es are arranged with overlapping ends. If the distance between the upper and the lower chord is made to decrease from the xed end to the free end, a self-supporting spar forming a body of substantially uniform strength is obtained. Y In the drawing affixed to this specification and forming part thereof some glrders embodying my invention are illustrated diatically by way Y of example.

In the drawing Fig. 1 is a cross section of a girder formed with three webs,

Fig. 2 is a similar view of a. glrder having two webs,

Figs. 3, 4 and 5 are cross sections of the gli-der shown in Figs. 6 and '1, having a diierent number of webs in diierent parts of its length, these gures being sections along the lines 3 8, d-Ji and 5 5, respectively, oi Fig. 6,

Fig. 6 is a side elevation and Fig. 7 is a plan view or this girder.

anges 2 extending at right angles from the body portions and having substantially rectangular cross section. 3 are the webs secured to the flanges 2, each web being fixed to each flange by a single row of rivets only. Each chord is formed with three iianges `and to each iiange a web is fixed. Y

In Figs. 2 and 3 each chord l is provided with four and five flanges 2, respectively, two webs being ixed to the outer anges near the fixed end of the girder, while near the free end shown in `Fig. 4 the webs are secured to the inner flanges, the outer portions (shown'in dotted lines) of the chords being removed by milling or the like. If desired, the chords may taper towards their free ends in such manner that only a single flange remains over to which a single web is secured as shown in Fig. 5. It should be understood that Figs. 3, 4 and 5 are cross sections of the inner,

middle and outer portions of one and the same girder. The width of the chords diminishes also as shown in Fig. 7, either uniformly as shown at the upper contour line or in steps as shown at the lower contour line The upper contour line i is shown as a straight line but may be curved ii desired, for instance, parabolically.' The webs 3 are here shown as openwork metal sheets, those at the inner end of the glrder being secured to the outer anges, those in the middle and at the free end to the inner anges, theends of adjoining webs overlapping each other, as can best be seen in Fig. 's'.

I wish it to be understood that'I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.

. I claim:

1. A girder comprising a pair of chords and a. plurality of substantially parallel webs which are materially shorter than said chords, each chord being formed Vwith at least three longitudinal anges extending substantially at right angles to said chords, a web being fixed to each outer flange of each chord and extending from one end towards but short of the middle of such chord, and a web fixed to the inner ange of each chord and' extending fron the other end towards the middle of such chord.

2. A girder comprising a pair oi' chords and i'lve substantially parallel webs which are. materially shorter than said chords. each chord being formed with ve flanges extending substantially at right angles to said chords, two such webs being fixed to the outer flanges and extending from one end of and towards, but short of the middle of each chord, two other such webs being ilxed to the adjoining flanges and extending only over the middle portion of each chord,` the ilfth web being fixed to thermiddle ilanges of such chords and extending from the other ends towards, but short oi' the middle of each chord.

3. A girder fixed at one end comprising a pair o! chords and a plurality of substantially parallel' which are materially shorter than said chords,

each chord being formed with live `ilanges extending substantially at right angles to said chords, two such webs being fixed to the outer' flanges and extending from the iixed end of and towards, but short of the middle of each chord, two other such webs being fixed to the adjoining ilanges and rextending only over the middle portion of each chord, the fifth web being iixed to the middle tla'nges of such chords and extending from the free ends towards. but short of the middle oi.' each chord.

5. A girder having a fixed end and a free end comprising a pair of chords provided with a plurality of spaced, longitudinally extending flanges, said chords being tapered in width thereby reducing the number oi.' said flanges 4at said free end, and a series of short, overlapping, spaced webs secured to the marginal flanges along the length of said girder and uniting said chords.

6. A girder comprising a pair oi' chords tapered in width towards one end and provided with a plurality of spaced substantially parallel longitudinally extending flanges, a plurality oi' longitudinally extending webs secured to saidflanges and uniting said chords, said webs being short and overlapped and their spacing being reduced towards said tapered end.

7. A girder comprising a pair of chords tapered in width towards one end and provided with a plurality oi spaced, longitudinally extending ilanges, a plurality of longitudinally extending webs distributed substantially discontinuously between said chords, secured to said ilanges and uniting said chords, the spacing of said webs being reduced toward said tapered end. Y

8. The structure of claim 7 wherein the distance between the chords is reduced at the tapered end oi said girder.

9. A girder having a ilxed end and a free end comprising a pair of chords provided with a plurality of spaced,longitudinal ilanges on one side of each chord,v a plurality of longitudinally extending webs distributed substantially discontinuously between said chords, secured to said flanges and uniting said chords, the number and spacing of said webs being reduced toward the free end of said girder. I

l0. A girder having a xed end and a free end comprising a pair of chords provided with a plurality of spaced longitudinal flanges on one side of each chord, a plurality of longitudinally extending webs, distributed substantially discontinuously between said chords, secured to said flanges and uniting said chords. the number and spacing oi' said webs being reduced toward said free end, said webs being secured to the outermost ilanges at said ilxed end and to inner iianges at said free end.

CLAUDE DORNIER. 

